KR20170009940A - Method for determining abnormality in battery pack, and device for determining abnormality in battery pack - Google Patents

Abstract

The present invention relates to a method for judging an abnormality of a battery module in which a plurality of parallel cells constituted by connecting a plurality of secondary battery cells (2) in series are connected in series, Detects the expansion of each of the secondary battery cells (2) by the detection sensor (5), and based on the expansion detected from the two or more secondary battery cells (2) It is determined that an abnormality has occurred.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for determining an abnormality of a battery,

The present invention relates to an abnormality determination method and an abnormality determination apparatus of a battery assembly (battery assembly) constructed by connecting a plurality of parallel units constituted by connecting a plurality of secondary battery cells in parallel.

Description of the Related Art [0002] Recently, a sealed secondary battery typified by a lithium ion secondary battery has been used not only as a mobile device such as a cellular phone or a notebook computer, but also as a power source for an electric vehicle such as an electric car or a hybrid vehicle. A cell constituting a secondary battery, that is, a secondary battery cell (also referred to as a single cell) is an electrode group formed by winding (winding) or stacking a positive electrode and a negative electrode with a separator therebetween And an external unit for accommodating the electrode group. Generally, a laminate film or a metal can is used as an external body, and an electrode group is accommodated together with an electrolytic solution in a sealed space inside.

In applications where a high voltage is required as in the case of the power source for the electric vehicle described above, a battery module formed by housing a built-in battery constituted by a plurality of secondary battery cells is used. Generally, such a rechargeable battery is constituted by connecting a plurality of parallel units of secondary battery cells in series. For example, a so-called two-parallel-two-series battery in which two parallel cells connected in parallel are connected in series is used. A battery module mounted on a vehicle is used in the form of a battery pack. In the battery pack, a plurality of battery modules connected in series are housed in a case together with various devices such as a controller.

However, if an abnormality occurs in any of the secondary battery cells constituting the assembled battery, it may lead to a problem. For example, when the electrolyte is decomposed due to an overcharge failure, the secondary battery cell expands due to the increase of the internal pressure due to the decomposition gas, and if the charge / discharge is not blocked as it is, ignition or rupture is caused. In order to avoid such a problem, it is not sufficient merely to determine whether or not there is an abnormality. Thus, a method of specifying which secondary battery cell among the secondary battery cells constituting the battery module is abnormal Is desired. Further, it is more preferable that it is possible to estimate the above-mentioned type.

Patent Literatures 1 and 2 disclose an apparatus for determining an abnormality of a battery module in which a plurality of secondary battery cells are connected in series. Patent Document 3 discloses an apparatus for determining deterioration of a battery. However, since these devices perform determination based on various voltages, they may not be suitable for a battery module including a parallel body of secondary battery cells. That is, since the voltages of the secondary battery cells in the parallel relationship are equal to each other, it is difficult to discriminate which secondary battery cell is abnormal and the detection accuracy is lowered.

Patent Document 4 discloses a method of measuring a stress change of a secondary battery cell using a strain gauge and detecting a completion time of charging based on the measured stress change. However, this method is merely to detect a change in stress from a normal secondary battery cell, and it can not be determined that an abnormality has occurred in the secondary battery cell. In addition, it is considered impossible to specify which secondary battery cell among the secondary battery cells constituting the battery unit has caused an abnormality.

Japanese Patent Application Laid-Open No. 2001-25173 Japanese Patent Application Laid-Open No. 2007-18871 Japanese Patent Application Laid-Open No. 2002-345164 Japanese Patent Application Laid-Open No. H05-326027

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide a battery pack including a parallel body of secondary battery cells in which abnormalities occur in a specific secondary battery cell And to provide an apparatus for determining the abnormality of a battery module.

A method of determining a battery abnormality according to the present invention is a method of determining the abnormality of a battery in which a plurality of parallel bodies constituted by connecting a plurality of secondary battery cells in parallel are connected in series, Each of the secondary battery cells is detected by the detection sensor attached to the secondary battery cell and based on the expansion detected from the two or more secondary battery cells, it is determined that an abnormality has occurred in a specific secondary battery cell among them will be.

In the abnormality determination method, based on each expansion of the secondary battery cells, it is determined that an abnormality has occurred in a specific secondary battery cell among the secondary battery cells. The expansion of the secondary battery cell is detected by a detection sensor attached to each of the secondary battery cells constituting the battery module. The present inventors have paid attention to the fact that when the overcharge abnormality or other abnormality occurs, various phenomena are observed with respect to the expansion of the secondary battery cell, A method of determining abnormality of a specific secondary battery cell with respect to the assembled battery including the parallel body of the secondary battery cell is devised by using the aspect as an index.

Further, an apparatus for determining the abnormality of a battery in a battery according to the present invention is an apparatus for determining the abnormality of a battery in which a plurality of parallel bodies constituted by connecting a plurality of secondary battery cells in parallel are connected in series, A detection sensor attached to each of the cells and detecting an expansion of the secondary battery cell; and a determination unit that determines that an abnormality has occurred in a specific secondary battery cell among them based on the expansion detected from the two or more secondary battery cells And an abnormality judging means for judging the abnormality. Thus, an apparatus for realizing the abnormality determination method is provided.

In the abnormality determination method or the abnormality determination device for a battery module according to the present invention, the following first to fourth embodiments are conceivable as concrete determination processing concerning occurrence of abnormality in the secondary battery cell.

In the first aspect, during filling, the expansion of the first secondary battery cell is larger than the expansion of the secondary battery cell in series with the first secondary battery cell, and the expansion of the first secondary battery cell When the expansion of the second secondary battery cell in parallel with the second secondary battery cell is smaller than the expansion of the secondary battery cell in series with the second secondary battery cell, Is determined to have occurred. It is estimated that a resistance abnormality has occurred in the second secondary battery cell.

When the first and second secondary battery cells are in a parallel relation, for example, when a resistance abnormality occurs in the second secondary battery cell, the first secondary battery cell bulges greatly during charging. This is because a large amount of current flows through the first secondary battery cell due to the increase of the resistance of the second secondary battery cell because the voltages are equal between the secondary battery cells connected in parallel. Further, expansion of the first secondary battery cell is larger than expansion of the normal secondary battery cell in series with them, and expansion of the second secondary battery cell is smaller. Therefore, according to the first aspect, the secondary battery cell causing the resistance abnormality is specified.

In the second aspect, during charging, the rate of expansion of at least one secondary battery cell is higher than the predetermined value, and the rate of expansion of the other at least two secondary battery cells is lower than the predetermined value ( It is determined that an abnormality has occurred in the secondary battery cell whose rate of expansion exceeds a predetermined value. It is estimated that an overcharge failure has occurred in the secondary battery cell where the rate of expansion exceeds the predetermined value.

When the rechargeable battery cell is normal, the expansion of the rechargeable battery cell is mainly caused by a change in the volume of the active material (active material). On the other hand, in the secondary battery cell in which the overcharge abnormality occurs, the expansion is promoted by the decomposition gas of the electrolytic solution, so that the rate of expansion (the amount of change in expansion per unit time) is faster than the normal secondary battery cell. Therefore, when there is a secondary battery cell in which the rate of expansion exceeds a predetermined value and the rate of expansion of the other secondary battery cells is substantially equal to or less than the predetermined value, the rate of expansion exceeds the predetermined value There is a high possibility that an overcharge abnormality is generated in the secondary battery cell. As described above, according to the second aspect, the secondary battery cell causing the overcharge abnormality is specified.

In the third aspect, when the difference in expansion between the at least two secondary battery cells exceeds a predetermined value during a period of time when the secondary battery cell is not charged or discharged, Is determined to have occurred. It is presumed that an abnormality in gas generation occurs in the secondary battery cell having the larger expansion.

If all of the secondary battery cells are normal in a state of being in a non-charging / resting state, their depth of charge and their depth of discharge are equal to each other, and the amount of volume change of the active material contributing to charging and discharging will become the same. Therefore, when the difference in expansion between the two or more secondary battery cells is large enough to exceed the predetermined value, there is a high possibility that an abnormality in gas generation occurs in the secondary battery cell having the larger expansion. As described above, according to the third aspect, the secondary battery cell causing the gas generation abnormality is specified.

In the fourth aspect, the difference in the amount of change in expansion between two points of the charging depth in the same charge / discharge cycle, among the at least two secondary battery cells during a non-charging / , It is determined that an abnormality has occurred in the secondary battery cell having the smaller change amount of the expansion. It is presumed that the secondary battery cell having a smaller change amount of the expansion caused an abnormal deactivation of the active material.

By comparing the amount of change in expansion between two points having different charge depths in the same charge / discharge cycle in a state of being in a state of not being charged / discharged, it is possible to reduce the difference in the amount of gas generation in the secondary battery cell , It is possible to compare the amount of change in the volume of the active material with charge and discharge. Therefore, when the difference in the amount of change in expansion is large, the volume change amount of the active material is significantly different among the compared secondary battery cells. This means that there is a secondary battery cell in which the active material contributing to charging and discharging is reduced, and the secondary battery cell has a high possibility that an inactivation abnormality of the active material is generated. As described above, according to the fourth aspect, the secondary battery cell causing the inactivation failure of the active material is specified.

In order to avoid the problem caused by the abnormality of the secondary battery cell, it is preferable to interrupt the charging / discharging of the secondary battery according to the judgment that an abnormality has occurred in the secondary battery cell.

Wherein the detection sensor has a polymer matrix layer and the polymer matrix layer contains a filler dispersed in the polymer matrix layer to change the external field according to the deformation of the polymer matrix layer, It is preferable to detect the expansion of the secondary battery cell by the change of the casing depending on the deformation of the polymer matrix layer. As a result, the expansion of the secondary battery cell can be detected with high sensitivity, and occurrence of the abnormality can be judged with good accuracy.

In the above, it is preferable that the polymer matrix layer contains a magnetic filler as the filler, and the detecting section detects a change in the magnetic field as the exterior. This makes it possible to detect the change of the magnetic field due to the deformation of the polymer matrix layer without wiring. In addition, since a hall element having a wide sensitivity range can be used as a detecting portion, high sensitivity can be detected over a wider range.

1 is a block diagram showing a system having an abnormality determination apparatus according to the present invention.
2 is a perspective view showing an example of a secondary battery cell to which a detection sensor is attached.
3 is a graph for explaining the amount of change in expansion.
4 is a perspective view showing another example of a secondary battery cell equipped with a detection sensor.
5 is a cross-sectional view taken along line A-A of Fig.
6 is a perspective view showing another example of the secondary battery cell to which the detection sensor is attached.
7 is a cross-sectional view taken along line B-B of Fig.

Hereinafter, embodiments of the present invention will be described.

Fig. 1 shows a system mounted on an electric vehicle such as an electric car or a hybrid vehicle. The present system is provided with a battery module 1, which is a secondary battery capable of being charged and discharged, having an abnormality determination device which is an embodiment of the present invention. Although only one battery module 1 is shown, the battery module 1 is actually provided as a battery pack including a plurality of battery modules 1. In the battery pack, a plurality of battery modules 1 are connected in series, and these are contained in a case together with various devices such as a controller. The case of the battery pack is formed in a shape suitable for mounting the vehicle, for example, in a shape matched to the bottom shape of the vehicle.

In the battery module 1, a battery module constituted by a plurality of secondary battery cells 2 (hereinafter, sometimes simply referred to as " cell 2 ") is accommodated in a case. In the present embodiment, a so-called two-parallel, two-series battery composed of two parallel cells formed by two cells 2 connected in series is used. The constitution of the battery pack is not particularly limited as long as a plurality of parallel units constituted by connecting a plurality of secondary battery cells in parallel are connected in series. That is, three or more secondary battery cells constituting the parallel body may be provided, and three or more parallel bodies connected in series may be provided. In either case, the used battery is composed of four or more secondary battery cells.

2, the cell 2 is a sealed secondary battery in which an electrode group (not shown) is accommodated in a closed space in the casing 21. [ The electrode group has a structure in which an anode and a cathode are wound or laminated with a separator interposed therebetween, and an electrolyte is held in the separator. The external body 21 is a laminated film such as an aluminum laminate foil or the like, but a cylindrical or square metal can can be used instead. In this embodiment, the cell 2 is a laminate type lithium ion secondary battery having a capacity of 1.44 Ah (size: 90 mm in length x 30 mm in width x 4 mm in thickness).

The abnormality determination apparatus includes a detection sensor (5) and an abnormality determination means. The detection sensor 5 is attached to each of the cells 2 and detects the expansion of the cells 2. [ The abnormality determining means determines that an abnormality has occurred in a specific secondary battery cell among these, based on the expansion detected from the two or more cells (2). The signal detected by the detection sensor 5 is transmitted to the control circuit 6 so that information on each expansion of the cell 2 is supplied to the control circuit 6. [ The control circuit 6 performs the above determination based on the information. The abnormality determination means is realized by the control circuit 6 executing this determination processing.

As concrete determination processing, the following first to fourth aspects can be cited. The abnormality determining means is configured to execute at least one of the first to fourth aspects, and preferably all of them. For convenience of explanation, four cells 2 may be referred to as cells C1 to C4 in order to distinguish them.

The expansion of the cell C1 (an example of the first secondary battery cell) is larger than the expansion of the secondary battery cell in serial relation with the cell C1, and the cell C1 When the expansion of the cell C2 (an example of the second secondary battery cell) in parallel with the cell C2 is smaller than the expansion of the secondary cell in series with the cell C2, It is determined that an abnormality has occurred. In this case, it is assumed that a resistance abnormality has occurred in the cell C2. In addition, any of the cells C2 to C4 may correspond to the first secondary battery cell.

In the parallel cell including the cell C2 causing the resistance abnormality, the other cell C1 belonging to the parallel cell bulges greatly during charging by the constant current as the battery module 1. [ This is because voltages are equal to each other between the cells C1 and C2 which are in parallel relation to each other, so that a large amount of current flows through the cell C1 to increase the depth of charge as the resistance of the cell C2 increases . Compared to the expansion of the normal cells C3 and C4 in series with these, the expansion of the cell C1 becomes larger and the expansion of the abnormal cell C2 becomes smaller. Therefore, in the first aspect, the secondary battery cell causing the resistance abnormality is specified.

The secondary battery cell in series with the cell C1 and the secondary battery cell in series with the cell C2 may be any of the cells C3 and C4, It is preferable to use a battery cell as the target. However, since the expansion of the cells (C3, C4) is substantially the same as that of the cells (C3, C4), the secondary battery cells for comparing expansion with the cells (C1, C2) do not have to be the same. Further, when the expansion is compared, a predetermined value set in advance as the tolerance range can be considered.

As described above, if the expansion of the cell C1 is greater than the expansion of the cell C3 (or C4) and the expansion of the cell C2 is less than the expansion of the cell C3 (or C4) It is determined that an abnormality has occurred. At this time, it may be added to the condition that the difference between the expansion of the cell C1 and the expansion of the cell C2 exceeds a predetermined value. Alternatively or additionally, the difference between the expansion between the cell C1 and the cell C3 (or C4) and the expansion between the cell C2 and the cell C3 (or C4) May be added to the condition.

In the case where the cell C2 is normal and any secondary battery cell other than the cell C2 is abnormal, an abnormality has occurred in a specific secondary battery cell (any one of the cells C1, C3, and C4) It is preferable that such a determination process is performed on the basis of the expansion of all of the cells C1 to C4 constituting the assembled battery.

As described above, in the first embodiment, it can be determined that an abnormality has occurred in a specific secondary battery cell (cell C2 in the above example) among the cells C1 to C4 constituting the battery module. A resistance error is estimated.

In the second aspect, it is preferable that, during charging, the rate of expansion of at least one secondary battery cell exceeds a predetermined value, and the rate of expansion of at least two other secondary battery cells falls below the predetermined value, , It is determined that an abnormality has occurred in the secondary battery cell whose rate of expansion exceeds a predetermined value. In this case, it is estimated that an overcharge failure has occurred in the secondary battery cell where the rate of expansion exceeds the predetermined value. The rate of expansion represents the amount of change in expansion per unit time.

For example, when the rate of expansion of the cell C1 is higher than the predetermined value and the rate of expansion of the other at least two secondary battery cells is below the predetermined value and substantially equal to each other, It is determined that an abnormality has occurred. The other at least two secondary battery cells may be any combination of the cells C2 to C4, but preferably include all the secondary battery cells other than the cell C1. The predetermined value is a value obtained in advance experimentally as a rate of expansion in a secondary battery cell in which an overcharge fault has occurred.

When an overcharge abnormality is generated in the cell C1, expansion of the cell C1 is promoted by the decomposition gas of the electrolytic solution, and the rate of expansion is faster than that of the normal cells C2 to C4. In the cells (C2 to C4), the expansion due to the volume change of the active material caused by the charging is caused, but the rate is slow compared with the expansion due to the overcharge failure. Therefore, if there is a cell C1 having a rate of expansion exceeding a predetermined value and the rate of expansion of the other cells C2 to C4 is substantially equal to or less than the predetermined value, Is likely to occur. Therefore, in the second aspect, the secondary battery cell causing the overcharge abnormality is specified.

When the cell C1 is normal and any other secondary battery cell is abnormal, it is judged that an abnormality has occurred in a specific secondary battery cell (any of the cells C2 to C4) among them Such a determination process is preferably performed based on the expansion of all the cells (C1 to C4) constituting the assembled battery.

As described above, in the second embodiment, it can be determined that an abnormality has occurred in a specific secondary battery cell (cell C1 in the above example) among the cells C1 to C4 constituting the battery module. An overcharge abnormality is estimated.

In the third aspect, when the difference in expansion between the at least two secondary battery cells exceeds the predetermined value during the non-charging / discharging stop, an abnormality has occurred in the secondary battery cell having the larger expansion therein . In this case, it is estimated that an abnormality in gas generation occurs in the secondary battery cell having the larger expansion.

For example, if the difference between the expansion of the cell C1 and the expansion of the cell C2 is greater than the predetermined value during stoppage and the expansion of the cell C1 is larger than the predetermined value, an abnormality has occurred in the cell C1 . The combination of the secondary battery cells to be compared is not particularly limited and may be compared between the secondary battery cells in the parallel relationship or between the secondary battery cells in the series relationship. The predetermined value is a value obtained in advance experimentally as a difference in expansion between a cell causing a gas generation abnormality and a cell not causing gas abnormality.

If all of the cells C1 to C4 are normal during stoppage, their charge depth and discharge depth are equal to each other, and the volume change amount of the active material contributing to charging and discharging will be the same. Therefore, when the difference between the expansion of the cell C1 and the expansion of the cell C2 is larger than the predetermined value and the expansion of the cell C1 is larger than the predetermined value, There is a high possibility that an abnormality has occurred. Therefore, in the third aspect, the secondary battery cell causing the gas generation abnormality is specified.

When the cell C1 is normal and any other secondary cell is abnormal, it is judged that an abnormality has occurred in a specific secondary battery cell (any one of the cells C2 to C4) among them Such a determination process is preferably performed based on the expansion of all the cells (C1 to C4) constituting the assembled battery.

As described above, in the third embodiment, it can be determined that an abnormality has occurred in a specific secondary battery cell (cell C1 in the above example) among the cells (C1 to C4) constituting the assembled battery. An abnormality of gas generation is estimated.

In the fourth aspect, the difference in the amount of change in expansion between two points of the charging depth in the same charge / discharge cycle, among the at least two secondary battery cells during a non-charging / , It is determined that an abnormality has occurred in the secondary battery cell having the smaller change amount of the expansion. In this case, it is estimated that an inactivation failure of the active material occurs in the secondary battery cell having a smaller amount of expansion change.

The amount of change in expansion between the two points having different charging depths in the same charge / discharge cycle is compared in a state of being in a state of not being charged / discharged, so that the difference in the amount of gas generation for each secondary battery cell can be ignored , And the amount of change in the volume of the active material due to charging and discharging can be compared. Therefore, when the difference in the amount of change in expansion is large, the volume change amount of the active material is significantly different among the compared secondary battery cells. This means that there is a secondary battery cell in which the active material contributing to charging and discharging is reduced, and the secondary battery cell has a high possibility that an inactivation abnormality of the active material is generated. Therefore, according to the fourth aspect, the secondary battery cell causing the inactivation failure of the active material is specified.

Here, the case where the expansion of the cells C1 to C3 is in the relation of Fig. 3 is exemplified. The abscissa of the graph indicates the number of cycles of charging and discharging, and is shown up to the third cycle of charging and discharging. The vertical axis of the graph is the expansion of the secondary battery cell and is detected as a change in magnetic flux density (change in magnetic field) in the detection sensor 5 using magnetism as described later. For convenience of explanation, the expansion of the cell C4 is not described, but in practice, it is preferable to determine all the secondary battery cells constituting the battery including the expansion of the cell C4.

In the example shown in Fig. 3, between the points A and B where the charge depths in the same charge / discharge cycle are different from each other and between the points A and B, (T1 to t3) of the expansion amounts of the first to third cylinders C1 to C3 are calculated. The two points having different charge depths are appropriately selected from the point of time at which they are stopped in the same charge / discharge cycle. When the difference between the expansion amounts t1 and t3 exceeds the predetermined value and the difference between t1 and t3 exceeds the predetermined value, it is assumed that the volume change amount of the active material is significantly different between the cells C1 and C3 . Then, in the cell C3 in which the amount of change in the expansion is small, inactivity abnormality of the active material is judged because the active material contributing to charging and discharging is reduced. The predetermined value is a value obtained in advance experimentally as a difference between the amount of change in the expansion between the cell causing the inactivating abnormality of the active material and the cell not causing it.

If a difference in the amount of gas generation occurs between the secondary battery cells, a difference occurs in the value of the expansion (the value of the vertical axis). By comparing the amounts of expansion t1 to t3 as described above, The difference in the amount of gas generation of the gas is negligible. For example, although there is a difference in the value of expansion (the value of the vertical axis) between the cell C1 and the cell C2, by using the amounts of change t1 and t2 of the expansion, Under the condition, the volume change amount of the active material can be compared. In this example, since the amounts of change t1 and t2 of the expansion are substantially the same, the inactivation of the active material is not determined in the cell C2.

As described above, in the fourth aspect, it can be determined that an abnormality has occurred in a specific secondary battery cell (cell C3 in the above example) among the cells (C1 to C4) constituting the battery module. The deactivation of the active material is estimated.

The abnormality determination apparatus of the present embodiment is provided with a blocking means for blocking the charge and discharge of the assembled battery in accordance with the determination that an abnormality has occurred in the cell 2 so as to avoid the problem caused by the abnormality of the cell 2 do. Specifically, when the control circuit 6 determines that an abnormality has occurred in any one of the cells (C1 to C4) in the cell (2), it sends a signal to the switching circuit (7) The current from the charging device 8 is cut off, and the charge / discharge of the assembled battery is cut off. The blocking means is realized by the control circuit 6 executing this processing.

In the present embodiment, the detection sensor 5 as shown in Fig. 2 is attached to the cell 2. Fig. The detection sensor 5 includes a polymer matrix layer 3 attached to the cell 2 and a detection unit 4. The detection unit 5 includes a light- The polymer matrix layer 3 contains a filler dispersed in the polymer matrix layer 3 to give a change in the sheath in accordance with the deformation of the polymer matrix layer 3 and the detection section 4 detects a change in its sheath. When the cell 2 is swollen to deform the polymer matrix layer 3, the change in the sheath due to the deformation of the polymer matrix layer 3 is detected by the detection unit 4. In this manner, the expansion of the cell 2 is detected by the detection sensor 5.

The polymer matrix layer 3 is formed of an elastomer material or the like capable of flexible deformation due to expansion of the cell 2. The polymer matrix layer 3 is formed into a sheet shape having a size of, for example, 5 mm in length x 30 mm in width x 1.0 mm in thickness, and an adhesive or an adhesive tape is used to attach the polymer matrix layer 3 if necessary. The detecting unit 4 is disposed at a position where a change in the exterior can be detected, and is preferably attached to a relatively rigid area that is not easily affected by the expansion of the cell 2. [ In the present embodiment, the detecting portion 4 is attached to the inner surface of the case (not shown) of the battery module 1, but it may be attached to another portion such as an outer surface of the case. The case of the battery module 1 is formed of, for example, metal or plastic, and a laminate film may be used.

In the example of Fig. 2, the polymer matrix layer 3 is attached to the outer surface of the sheath 21, but the polymer matrix layer 3 may be disposed at other portions as long as the expansion of the cell 2 can be detected, It is also possible to dispose it inside the cell 2. The expansion of the cell to be detected is caused not only by an increase in the internal pressure caused by the expansion of the gas when the overcharge abnormality occurs but also due to the expansion of the electrode due to the deactivation of the electrode active material such as graphite .

In the examples of Figs. 4 and 5, the polymer matrix layer 3 is attached to the electrode group 22. The electrode group 22 has a structure in which an anode and a cathode are wound with a separator interposed therebetween. The polymer matrix layer 3 is present between the external body 21 and the electrode group 22 and may be detached from the internal surface of the external body 21. [ When the electrode group 22 expands and the polymer matrix layer 3 is deformed, a change in the outer envelope is detected by the detecting unit 4. [ Accordingly, the expansion of the cell 2 due to the expansion of the electrode is detected by the detection sensor 5. [ Although the detecting portion 4 is attached to the outer surface of the outer casing 21, it may be attached to the case of the battery module as shown in Fig.

In the examples of Figs. 6 and 7, the polymer matrix layer 3 is attached to the inner surface of the sheath 21 and disposed so as not to contact the electrode group 23. The electrode group 23 has a structure in which an anode and a cathode are stacked with a separator interposed therebetween. When the polymer matrix layer 3 is deformed due to the rise of the pressure due to the generation of the decomposition gas, the change in the envelope is detected by the detecting section 4. Although the detecting portion 4 is attached to the outer surface of the outer casing 21, it may be attached to the case of the battery module as shown in Fig.

In the present embodiment, the polymer matrix layer 3 contains a magnetic filler as the filler, and the detecting section 4 detects a change in the magnetic field as the sheath. In this case, the polymer matrix layer 3 is preferably a magnetic elastomer layer in which a magnetic filler is dispersed in a matrix composed of an elastomer component.

Examples of the magnetic filler include a rare earth element, an iron element, a cobalt element, a nickel element, an oxide element and the like, and a rare earth element in which a higher magnetic force can be obtained is preferable. The shape of the magnetic filler is not particularly limited and may be spherical, flat, needle-like, columnar, or amorphous. The average particle diameter of the magnetic filler is preferably 0.02 to 500 占 퐉, more preferably 0.1 to 400 占 퐉, and still more preferably 0.5 to 300 占 퐉. When the average particle diameter is smaller than 0.02 탆, the magnetic properties of the magnetic filler tend to be lowered. When the average particle diameter exceeds 500 탆, the magnetic properties of the magnetic elastomer layer tend to be lowered.

The magnetic filler may be introduced into the elastomer after magnetization, but is preferably magnetized after being introduced into the elastomer. The polarity of the magnet is easily controlled by magnetization after introduction into the elastomer, and detection of the magnetic field is facilitated.

As the elastomer component, a thermoplastic elastomer, a thermosetting elastomer, or a mixture thereof can be used. Examples of the thermoplastic elastomer include thermoplastic elastomers such as a styrene thermoplastic elastomer, a polyolefin thermoplastic elastomer, a polyurethane thermoplastic elastomer, a polyester thermoplastic elastomer, a polyamide thermoplastic elastomer, a polybutadiene thermoplastic elastomer, a polyisoprene thermoplastic elastomer, . Examples of the thermosetting elastomer include diene-based synthetic rubbers such as polyisoprene rubber, polybutadiene rubber, styrene-butadiene rubber, polychloroprene rubber, nitrile rubber and ethylene-propylene rubber, ethylene-propylene rubber, butyl rubber, Non-diene synthetic rubbers such as urethane rubber, fluorine rubber, silicone rubber and epichlorohydrin rubber, and natural rubbers. Among these, preferred is a thermosetting elastomer because it can suppress the plastic deformation of the magnetic elastomer due to heat generation or overload of the battery. More preferably, it is a polyurethane rubber (also referred to as a polyurethane elastomer) or a silicone rubber (also referred to as a silicone elastomer).

The polyurethane elastomer is obtained by reacting a polyol and a polyisocyanate. When a polyurethane elastomer is used as an elastomer component, an active hydrogen-containing compound and a magnetic filler are mixed, and an isocyanate component is mixed therewith to obtain a mixed solution. It is also possible to obtain a mixed solution by mixing a magnetic filler with an isocyanate component and mixing an active hydrogen-containing compound. The mixed solution is poured into a mold which is subjected to a releasing treatment, and the mixture is heated to a curing temperature for curing, whereby a magnetic elastomer can be produced. When the silicone elastomer is used as the elastomer component, the magnetic elastomer can be prepared by mixing and mixing the precursor of the silicone elastomer with a magnetic filler, and then heating and curing the mixture. If necessary, a solvent may be added.

As the isocyanate component which can be used for the polyurethane elastomer, a compound known in the field of polyurethane can be used. Examples of the diisocyanate include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate , Aromatic diisocyanates such as 1,5-naphthalene diisocyanate, p-phenylenediisocyanate, m-phenylenediisocyanate, p-xylylene diisocyanate and m-xylylene diisocyanate, ethylene diisocyanate, 2,2,4- Aliphatic diisocyanates such as trimethyl hexamethylene diisocyanate and 1,6-hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, Nor And alicyclic diisocyanates such as boranediisocyanate. These may be used alone or in combination of two or more. The isocyanate component may be modified such as urethane-modified, allophanate-modified, buret-modified and isocyanurate-modified. Preferred isocyanate components are 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, more preferably 2,4-toluene diisocyanate, 2,6- Isocyanate.

As the active hydrogen-containing compound, those conventionally used in the technical field of polyurethane can be used. Examples thereof include polyether polyols such as polytetramethylene glycol, polypropylene glycol, polyethylene glycol, copolymers of propylene oxide and ethylene oxide, polybutylene adipate, polyethylene adipate, 3-methyl-1,5- A polyester polycarbonate polyol exemplified by a reaction product of a polyester glycol such as polycaprolactone polyol and polycaprolactone and an alkylene carbonate represented by a phenol, a polycarbonate polyol such as a polycaprolactone polyol, a polycarbonate polyol, an ethylene carbonate, A polyester polycarbonate polyol obtained by reacting the resulting reaction mixture with an organic dicarboxylic acid, and a high molecular weight polyol such as a polycarbonate polyol obtained through an ester exchange reaction between a polyhydroxyl compound and an aryl carbonate. These may be used alone, or two or more of them may be used in combination.

As the active hydrogen-containing compound, in addition to the above-mentioned high molecular weight polyol component, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4 1,2-butanediol, diethylene glycol, triethylene glycol, 1,4-bis (2-hydroxyethoxy) benzene, trimethylolpropane, glycerin, (Hydroxymethyl) cyclohexanol, diethylene glycol, triethylene glycol, triethylene glycol, hexane triol, pentaerythritol, tetramethylolcyclohexane, methyl glucoside, sorbitol, mannitol, dulcitol, sucrose, And low-molecular-weight polyol components such as triethanolamine, and low-molecular-weight polyamine components such as ethylenediamine, trilendiamine, diphenylmethanediamine, and diethylenetriamine. These may be used alone, or two or more of them may be used in combination. Further, it is also possible to use 4,4'-methylenebis (o-chloroaniline) (MOCA), 2,6-dichloro-p-phenylenediamine, 4,4'-methylenebis (2,3-dichloroaniline) Bis (methylthio) -2,6-toluenediamine, 3,5-diethyltoluene-2,4-diamine, 3,5-di Bis (2-aminophenylthio) ethane, tetraethylene glycol di-p-aminobenzoate, ethyltoluene-2,6-diamine, trimethylene glycol- Diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane, N, N'-di-sec-butyl-4,4'- diaminodiphenylmethane, 4,4 ' Diamino-3,3'-diethyldiphenylmethane, 4,4'-diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane, 4,4'- , 3'-diisopropyl-5,5'-dimethyldiphenylmethane, 4,4'-diamino-3,3 ', 5,5'-tetraethyldiphenylmethane, 4,4'- 3,3'-5,5'-tetraisopropyldiphenylmethane, m-xylylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, Diamines, and polyamines exemplified by p-xylylenediamine and the like. Preferred active hydrogen-containing compounds are polytetramethylene glycol, polypropylene glycol, copolymers of propylene oxide and ethylene oxide, polyester polyols comprising 3-methyl-1,5-pentanediol and adipic acid, Preferably, polypropylene glycol, a copolymer of propylene oxide and ethylene oxide.

A preferable combination of the isocyanate component and the active hydrogen-containing compound is a combination of at least one of 2,4-toluene diisocyanate, 2,6-toluene diisocyanate and 4,4'-diphenylmethane diisocyanate as the isocyanate component And a combination of at least one of polytetramethylene glycol, polypropylene glycol, a copolymer of propylene oxide and ethylene oxide, and 3-methyl-1,5-pentane adipate as the active hydrogen-containing compound. More preferably, as the isocyanate component, a copolymer of 2,4-toluene diisocyanate and / or 2,6-toluene diisocyanate and polypropylene glycol and / or propylene oxide and ethylene oxide as the active hydrogen- It is a combination.

It is also possible to provide a sealing material for sealing the polymer matrix layer 3 so as not to impair the flexibility of the polymer matrix layer 3 for the purpose of anticorrosive or the like of the magnetic filler . As the sealing material, a thermoplastic resin, a thermosetting resin, or a mixture thereof can be used. Examples of the thermoplastic resin include thermoplastic elastomers such as a styrene thermoplastic elastomer, a polyolefin thermoplastic elastomer, a polyurethane thermoplastic elastomer, a polyester thermoplastic elastomer, a polyamide thermoplastic elastomer, a polybutadiene thermoplastic elastomer, a polyisoprene thermoplastic elastomer, a fluorine thermoplastic elastomer, Acrylic acid ethyl copolymer, ethylene-vinyl acetate copolymer, polyvinyl chloride, polyvinylidene chloride, chlorinated polyethylene, fluororesin, polyamide, polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, Polybutadiene, and the like. Examples of the thermosetting resin include diene-based synthetic rubbers such as polyisoprene rubber, polybutadiene rubber, styrene-butadiene rubber, polychloroprene rubber and acrylonitrile-butadiene rubber, ethylene-propylene rubber, ethylene- Non-diene rubbers such as rubber, acrylic rubber, polyurethane rubber, fluorine rubber, silicone rubber and epichlorohydrin rubber, natural rubber, polyurethane resin, silicone resin and epoxy resin. Such a film may be laminated, or may be a film including a metal foil such as an aluminum foil or a metal vapor deposition film in which a metal is deposited on the film.

The polymer matrix layer 3 may be a foam containing dispersed fillers and bubbles. As the foam, a general resin foam can be used, but it is preferable to use a thermosetting resin foam in consideration of characteristics such as compression set distortion. Examples of the thermosetting resin foam include a polyurethane resin foam and a silicone resin foam, among which a polyurethane resin foam is suitable. For the polyurethane resin foam, the above-described isocyanate component or an active hydrogen-containing compound can be used.

The amount of the magnetic filler in the magnetic elastomer is preferably 1 to 450 parts by weight, more preferably 2 to 400 parts by weight, based on 100 parts by weight of the elastomer component. If it is less than 1 part by weight, the change of the magnetic field tends to be difficult to detect. If it exceeds 450 parts by weight, the magnetic elastomer itself may be sagged.

The polymer matrix layer 3 may be one in which the filler is localized in its thickness direction. For example, the polymer matrix layer 3 may have a structure in which two layers, that is, a region on one side where the filler is relatively large and a region on the other side where the filler is relatively small, are formed. In the region on one side containing a lot of fillers, the change of the sheath to the small deformation of the polymer matrix layer 3 becomes large, so that the sensitivity of the sensor to low withstand voltage can be increased. In addition, the region on the other side where the filler is relatively small is relatively flexible and easy to move. By attaching this region, the polymer matrix layer 3 (particularly, the region on one side) is easily deformed.

The filler misalignment rate in the region on one side is preferably more than 50, more preferably 60 or more, still more preferably 70 or more. In this case, the filler misalignment rate in the region on the other side is less than 50. The filler misalignment rate in one region is at most 100 and the filler misalignment rate in the other region is at least zero. Therefore, a laminate structure of an elastomer layer containing a filler and an elastomer layer not containing a filler may be used. A method of introducing a filler into an elastomer component and then allowing it to stand at room temperature or at a predetermined temperature and spontaneously precipitating it by the weight of the filler can be used for the localization of the filler. The filler ubiquitination rate can be adjusted. It is also possible to localize the filler by using physical force such as centrifugal force or magnetic force. Alternatively, the polymer matrix layer may be constituted by a laminate composed of a plurality of layers having different filler contents.

The filler grain fraction is measured by the following method. That is, the cross-section of the polymer matrix layer is observed at 100 times using a scanning electron microscope-energy dispersive X-ray analyzer (SEM-EDS). The amount of the metallic element inherent to the filler (for example, Fe element in the present embodiment) is determined by elemental analysis with respect to the entire region in the thickness direction of the section and the two regions in which the cross section is bisected in the thickness direction I ask. With respect to this abundance amount, the ratio of the area on one side to the entire area in the thickness direction is calculated, and this is taken as the filler misalignment rate in the area on one side. The filler misalignment rate in the region on the other side is also the same.

The region on the other side where the filler is relatively small may be formed of a foam containing bubbles. Thereby, the polymer matrix layer 3 is more easily deformed, and the sensor sensitivity is increased. In addition, the region on one side may be formed of a foam together with the region on the other side. In this case, the polymer matrix layer 3 as a whole becomes a foam. The polymer matrix layer in which at least part of the thickness direction is foamed may be composed of a laminate composed of a plurality of layers (for example, a non-foam layer containing a filler and a foam layer not containing a filler).

For example, a magnetic resistance element, a Hall element, an inductor, an MI element, a flux gate sensor, or the like can be used as the detecting portion 4 for detecting the change of the magnetic field. Examples of the magnetoresistive element include a semiconductor compound magnetoresistive element, an anisotropic magnetoresistive element (AMR), a giant magnetoresistive element (GMR), and a tunnel magnetoresistive element (TMR). Among these, a preferable hall element is a hall element, which has a high sensitivity over a wide range and is useful as the detecting portion 4. [ As the Hall element, for example, EQ-430L manufactured by Asahi Kasei Electronics Co., Ltd. can be used.

In the above-described embodiment, the example in which the secondary battery cell is a lithium ion secondary battery is shown, but the invention is not limited thereto. The secondary battery cell to be used is not limited to a nonaqueous electrolyte secondary battery such as a lithium ion battery and may be an aqueous electrolyte secondary battery such as a nickel hydride battery.

In the above-described embodiment, the detection sensor detects the expansion according to the change of the magnetic field, but it may be configured to use another change of the exterior such as an electric field. For example, a configuration in which the polymer matrix layer contains a conductive filler such as metal particles, carbon black, or carbon nanotubes as a filler, and the detecting portion detects a change in electric field (change in resistance and permittivity) as an exterior.

Any known pressure sensor or the like may be used as the detection sensor as long as it can detect the expansion of each of the secondary battery cells constituting the battery module. However, in order to detect the expansion of the secondary battery cell with high sensitivity, the above-described polymer matrix layer and the detection sensor provided with the detection portion are useful. In addition, outstanding.

The present invention is not limited in any way by the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

One; Battery module
2; Secondary battery cell
3; Polymer matrix layer
4; The detection unit
5; Detection sensor
6; Control circuit
7; Switching circuit
8; Generator or rechargeable power source
21; External body
22; Electrode group
23; Electrode group

Claims (16)

A method for determining an abnormality of a battery assembly comprising a plurality of parallel units connected in series by connecting a plurality of secondary battery cells in series, characterized in that a detection sensor attached to each of the secondary battery cells Wherein the abnormality detecting means detects the respective expansion of the secondary battery cells and determines that an abnormality has occurred in a specific secondary battery cell among them based on the expansion detected from the two or more secondary battery cells Way. The method according to claim 1,
During charging, the expansion of the first secondary battery cell is larger than the expansion of the secondary battery cell in series with the first secondary battery cell, and the expansion of the secondary battery cell in parallel with the first secondary battery cell When the expansion of the second secondary battery cell is smaller than the expansion of the secondary battery cell in series with the second secondary battery cell, An abnormality determination method of a battery. The method according to claim 1,
When the rate of expansion of at least one secondary battery cell is higher than a predetermined value and the rate of expansion of the other at least two secondary battery cells is substantially equal to or less than the predetermined value during charging, And determines that an abnormality has occurred in the secondary battery cell whose rate of expansion exceeds a predetermined value. The method according to claim 1,
It is judged that an abnormality has occurred in the secondary battery cell having the larger expansion in the case where the difference in expansion between the at least two secondary battery cells exceeds the predetermined value during the period of not charging / discharging A method for determining abnormalities in a battery module. The method according to claim 1,
When the difference in the amount of expansion between two at least two secondary battery cells in the same charge / discharge cycle is greater than a predetermined value during stoppage without charging / discharging In which the abnormality has occurred in the secondary battery cell in which the amount of change in expansion is small. 6. The method according to any one of claims 1 to 5,
Wherein the charge / discharge of the battery module is cut off in response to a determination that an abnormality has occurred in the secondary battery module. 7. The method according to any one of claims 1 to 6,
Wherein the detection sensor has a polymer matrix layer and the polymer matrix layer contains a filler dispersed in the polymer matrix layer to change the external field according to the deformation of the polymer matrix layer,
Wherein the polymer matrix layer is adhered to the secondary battery cell and the expansion of the secondary battery cell is detected by the change of the casing due to the deformation of the polymer matrix layer. 8. The method of claim 7,
Wherein the polymer matrix layer contains a magnetic filler as the filler, and the detecting section detects a change in magnetic field as the sheath. A battery abnormality determination device comprising a plurality of parallel cells constituted by connecting a plurality of secondary battery cells in parallel,
A detection sensor attached to each of the secondary battery cells to detect expansion of the secondary battery cell,
And abnormality determination means for determining based on the expansion detected from the two or more secondary battery cells that an abnormality has occurred in a specific one of the secondary battery cells. 10. The method of claim 9,
During charging, the expansion of the first secondary battery cell is larger than the expansion of the secondary battery cell in series with the first secondary battery cell, and the expansion of the secondary battery cell in parallel with the first secondary battery cell When the expansion of the second secondary battery cell is smaller than the expansion of the secondary battery cell in series with the second secondary battery cell, it is determined that the abnormality has occurred in the second secondary battery cell And an abnormality determination unit for determining an abnormality of the battery module. 10. The method of claim 9,
When the rate of expansion of at least one secondary battery cell is higher than a predetermined value and the rate of expansion of the other at least two secondary battery cells is substantially equal to or less than the predetermined value during charging, The abnormality determining means determines that an abnormality has occurred in the secondary battery cell whose rate of expansion exceeds a predetermined value. 10. The method of claim 9,
The abnormality determining means determines that abnormality has occurred in the secondary battery cell having the larger expansion in the case where the difference in expansion between the at least two secondary battery cells exceeds the predetermined value during the non-charging / The abnormality judging unit judges the abnormality of the battery. 10. The method of claim 9,
When the difference in the amount of change in expansion between two points of the charging depth in the same charge / discharge cycle is greater than a predetermined value in at least two secondary battery cells during a non-charge / The abnormality determination means determines that an abnormality has occurred in the secondary battery cell having a smaller change amount of the expansion of the battery. 14. The method according to any one of claims 9 to 13,
And a blocking means for blocking charging / discharging of the battery pack in accordance with a determination that an abnormality has occurred in the secondary battery cell. 15. The method according to any one of claims 9 to 14,
Wherein the detection sensor includes a polymer matrix layer attached to a secondary battery cell and a detection unit,
Wherein the polymer matrix layer contains a filler dispersed in the polymer matrix layer so as to cause changes in the sheath in accordance with deformation of the polymer matrix layer, and the detection section detects a change in the sheath. 16. The method of claim 15,
Wherein the polymer matrix layer contains a magnetic filler as the filler, and the detecting section detects a change of a magnetic field as the casing.

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